High-throughput screening assays for modulators of STAT4 and STAT6 activity

A method of screening for modulators of STAT6 binding to a STAT6 receptor, the method comprising:

• incubating a reaction mixture comprising a STAT6 polypeptide, a potential binding modulator, and a receptor peptide which comprises an amino acid sequence YX1X2X3 (SEQ ID NO:61), wherein the tyrosine is phosphorylated and:
• X1 is selected from the group consisting of K, V, R, I, M, and a first nonnatural amino acid;
• X2 is selected from the group consisting of P, A and S;
• and
• X3 is selected from the group consisting of W, Y, F, H, L and an aromatic second nonnatural amino acid;
• with the proviso that the peptide does not include the amino acid sequence YKPF (SEQ ID NO:2) or YKAF;
• and
• determining whether the binding of the STAT6 polypeptide to the receptor peptide is increased or decreased in comparison to an assay which lacks the potential binding modulator.